In general, a stay of this type includes a first arm turnably connected at a basal end part thereof to a skeleton, a second arm connected at a basal end part thereof to a leading end part of the first arm such that the second arm can turn between a development position and a folded position, a lock member disposed at the second arm in such a manner as to be movable toward and away from the first arm, and a lock biasing means for biasing the lock member toward the first arm. An engagement recess is formed in the leading end part of the first arm. When the second arm is turned to the development position, the lock member is brought into the engagement recess, thereby the second arm is locked at the development position. Moreover, since the lock member is biased toward the first arm by the lock biasing means, the locked state is reliably maintained. By this, the door is maintained in the open position. The locked state can be released by moving the lock member against the biasing force of the lock biasing means and bringing the lock member out of the engagement recess. In that state, the second arm can be turned from the development position toward the folded position. Accordingly, the door can be turned from the open position toward the closed position (see Japanese Utility Model Application Laid-Open No. S63-148777).
In the above-mentioned conventional stay, in case the door is to be turned from the open position toward the closed position by only one person, it is required for this person to maintain the escaped state of the lock member from the engagement recess with one hand, while turning the door toward the closed position with the other hand. This is a difficult job. This is particularly true when the door is large. In case two stays are used in order to cope with a large door, for example, in case two stays are installed one at the left side and the other at the right side of a door which is to be opened upward, the locked states of the two stays must be released simultaneously. It gives rise to a problem that the door cannot be turned from the open position toward the closed position by only one person.